Zinc One Piece Link System

ABSTRACT

A link jet system using a combination of a one piece cast zinc alloy case and interlocking linked shaped charges for minimizing debris left in a downhole wellbore when fired, reducing components in system, and providing an easy method for changing the shaped charge phase.

RELATED APPLICATIONS

This application is a continuation application of U.S. Nonprovisionalpatent application Ser. No. 15/508,614, filed Mar. 3, 2017 which is a371 of International Application No. PCT/US15/48667, filed Sep. 4, 2015which claims priority to U.S. Provisional Application No. 62/045,684,filed Sep. 4, 2014.

BACKGROUND OF THE INVENTION

Generally, when completing a subterranean well for the production offluids, minerals, or gases from underground reservoirs, several types oftubulars are placed downhole as part of the drilling, exploration, andcompletions process. These tubulars can include casing, tubing, pipes,liners, and devices conveyed downhole by tubulars of various types. Eachwell is unique, so combinations of different tubulars may be loweredinto a well for a multitude of purposes.

A subsurface or subterranean well transits one or more formations. Theformation is a body of rock or strata that contains one or morecompositions. The formation is treated as a continuous body. Hydrocarbondeposits may exist within the formation. Typically a wellbore is drilledfrom a surface location, placing a hole into a formation of interest.Completion equipment is placed downhole after drilling, includingcasing, tubing, and other downhole equipment as needed. Perforating thecasing and the formation with a perforating gun is a well known methodin the art for accessing hydrocarbon deposits within a formation from awellbore.

Explosively perforating the formation using a shaped charge is a widelyknown method for completing an oil well. A shaped charge is a term ofart for a device that when detonated generates a focused explosiveoutput. This is achieved in part by the geometry of the explosive inconjunction with an adjacent liner. Generally, a shaped charge includesa metal case that contains an explosive material with a shape and has athin metal liner on the inner surface of the explosive material. Manymaterials are used for the liner including brass, copper, tungsten, andlead. When the explosive detonates the liner metal is compressed into asuper-heated, super pressurized jet that can penetrate metal, concrete,and rock.

A perforating gun typically has a gun body. The gun body typically iscomposed of metal and is cylindrical in shape. Within a typical gun tubeis a charge holder or carrier tube, which is a tube that is designed tohold the actual shaped charges. The charge holder contains cutoutscalled charge holes where the shaped charges are placed.

A shaped charge is typically detonated by a booster or igniter. Shapedcharges may be detonated by electrical igniters, pressure activatedigniters, or detonating cord. One way to ignite several shaped chargesis to connect a common detonating cord that is placed proximate to theigniter of each shaped charge. The detonating cord is comprised ofmaterial that explodes upon ignition. The energy of the explodingdetonating cord can ignite shaped charges that are properly placedproximate to the detonating cord. Often a series of shaped charges maybe daisy chained together using detonating cord.

An alternative to using a perforating gun with a gun body is a stripsystem where the perforating charges are exposed to the downholeenvironment. The strip system may be conveyed downhole using coiledtubing. A strip system is smaller in diameter and allows for theperforation of casing where size is an issue. The strip system typicallymay include a series of shaped charges strung together along a loadingstrip. These shaped charges typically are individually sealed againstthe downhole environment. When the perforating charges are fired thesystem may break up, leaving debris inside the wellbore. The remains ofthe loading strip and anything attached is then removed from thewellbore.

SUMMARY OF EXAMPLES OF THE INVENTION

An example of the invention may include a linked perforating gun systemcomprising a plurality of shaped charges linked directly to each otherin a series, with each shaped charge having a shaped charge case andeach shaped charge case having a first stem and a second stem, whereinthe first stem and the second stem are 180 degrees opposed to each otherabout the center axis of the shaped charge case. A variation of theexample may include the first stem and second stem being integral to itsassociated shaped charge case. The first stem may also be a key. Thesecond stem may be a cylindrical socket with a plurality of internalslots adapted to accept a first stem from an adjacent shaped chare in acorresponding plurality of orientations. The second stem is may be asocket. The socket of the second stem may be configured to allow thefirst stem of an adjacent perforating shaped charge to interface withthe second stem at a plurality of phase angles. The example may furthercomprise a cap on each shaped charge adapted to seal the contents of theshaped charge from an outside environment. The cap may include an O-ringseal between each shaped charge and its associated cap. The plurality ofshaped charge cases and each accompanying first stem and second stem maybe composed of zinc alloy. The example may further comprise an extenderlocated between two of the plurality of shaped charge cases, wherein theextender is adapted to adjust the phase angle and shot density of theperforating gun system. The example may include a plurality of pinswherein the socket and the first stem have corresponding through holesthat when lined up will accept one of the plurality of pins toeffectively lock at least two shaped charges together. The extender maycontain a plurality of slots on a first end and key on the second end.The perforating shaped charge may each be individually sealed using acap placed over the charge case and using an O-ring to provide a watertight seal in a wellbore environment.

Another example of the invention may include a shaped charge comprisinga shaped charge case, an explosive material located within the case, aliner located such that the explosive material is between the liner andthe charge case, with the shaped charge case having a first stem and asecond stem, wherein the first stem and the second stem are 180 degreesopposed to each other. A variation of the example may include the firststem and second stem being integral to the shaped charge case. The firststem may be a male key. The second stem may be a cylindrical femalesocket. The first stem and second stem may be integral to a retainerring that snaps into place over the shaped charge case. The example mayfurther comprise a cap on the shaped charge adapted to seal the contentsof the shaped charge from an outside environment. The example mayfurther comprise an O-ring seal between each shaped charge and itsassociated cap. The shaped charge case, first stem, and second stem mayall be composed of a zinc alloy. The example may include each shapedcharge having a cap covering the opening of the shaped charge such thata water tight seal exist. The first stem may be a rectangular male key.The second stem may comprise a plurality of slots adapted to accept afirst stem at a plurality of angles.

An example of the invention may include a method for perforating awellbore comprising connecting a plurality of shaped charges directlytogether in a series, threading a detonating cord through each shapedcharge, lowering the plurality of shaped charges into a wellbore, andfiring the plurality of shaped charges at a predetermined locatingwithin the wellbore. A variation of the invention may include havingeach shaped charges interface with at last one other shaped charge. Theexample may further comprise phasing each shaped charge a predeterminednumber of degrees with respect to each other. It may further compriseadjusting the shot density of the plurality of shaped charges. It mayfurther comprise placing the plurality of shaped charges into aperforating gun tube.

Another example of the invention may include a linked perforating gunsystem comprising a plurality of shaped charge holder plates linkedtogether in series, each holder plate having a male end connector and afemale end connector. The example of the invention may have the femaleend connector adapted to accept a male end connector at a plurality ofphase angles. The example may further comprise a through hole on eachholder plate sized to fit a shaped charge at a first orientation. Theexample may have the shaped charge locked into place in the holder plateby rotating the shaped charge to a second orientation. The example mayfurther comprise a retainer adaptor to lock over a mated female and maleconnector. The retainer may lock by snapping two halves of the retainertogether over the mated female and male connectors. The retainer maylock by screwing two halves of the retainer together over the matedfemale and male connectors. The shaped charge holder plates may becomposed of zinc alloy. The linked shaped charge holder plates may beplaced inside a perforating gun body. The female end connector may be acylindrical disk attached perpendicular to the shaped charge holderplate and further comprising a plurality of slots arrayed such that eachslot may accept a male end connector.

Another example of the claimed invention may include a perforatingcharge holder comprising a first adaptor configured to hold aperforating shaped charge at a preselected phase angle and a secondadaptor configured to interface with a loading strip. The first adaptormay snap to a shaped charge case. The first adaptor may screw into ashaped charge case. The second adaptor may screw into the loading strip.The second adaptor may snap into the loading strip. The perforatingcharge holder may be composed of zinc alloy. The first adaptor may be aring. The second adaptor may be a ring like base. The example mayfurther include a first and second L-shaped member, each connected tothe base and the ring such that the two L-shaped members are mirrors ofeach other about a centerline of the circular base.

DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is madeto the following detailed description of the preferred embodiments,taken in conjunction with the accompanying drawings in which referencenumbers designate like or similar elements throughout the severalfigures. Briefly:

FIG. 1 is a shaped charge link system.

FIGS. 2A, 2B, and 2C are different views of a single link system shapedcharge.

FIG. 3 is an extender.

FIG. 4 is a connectable gun assembly.

FIG. 5 is an exploded view of a connectable gun assembly.

FIGS. 6A and 6C show an example of complete linked gun.

FIGS. 6B and 6D show an example retainer clip for the shaped charges.

FIG. 7 shows an example of a thin connectable gun assembly.

FIG. 8 shows an example of a single link for a thin connectable gun.

FIG. 9 shows an example of a twisted strip system.

FIG. 10 shows an example of a twisted loading strip.

FIG. 11 shows an example of a shape charge for use in a linked system.

DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION

In the following description, certain terms have been used for brevity,clarity, and examples. No unnecessary limitations are implied and suchterms are used for descriptive purposes only and are intended to bebroadly construed. The different apparatus and method steps describedherein may be used alone or in combination with other systems and methodsteps. It is to be expected that various equivalents, alternatives, andmodifications are possible within the scope of the appended claims.

In deep wells or long horizontal wells there is a need for smalldiameter perforation capabilities. Traditionally this was done using ametal loading strip attached to coiled tubing that had a series ofshaped charges screwed into place. The shaped charges may have a capthat seals the shaped charge from the downhole environment. This cap canbe constructed out of steel or zinc alloy. The loading strip is put intoplace and the shaped charges fired. Afterwards the loading strip isremoved from the well. Problems with prior designs include the fact thatthe debris from the perforating charges and the loading strip may remainin the well. A potential solution includes the current design which usesfrangible materials such as zinc alloys. Using zinc alloy for the shapedcharge cases, loading strip, and cap reduces the amount of large debrisleft in the wellbore. The shaped charge firing pulverizes the zinc alloyinto a powder.

Referring to an example shown in FIG. 1, a linked system 10 is shownusing shaped charge cases 11 connected together through a series ofinterlocking stems 12 and 80. Each shaped charge case 11 has an integralstem 12 that is adapted to fit within integral stem 80. Integral stem 12has a through hole 13. Integral stem 80 has a through hole 81. Whenintegral stem 12 is inserted into integral stem 80 a pin 14 may be usedto secure the integral stems together. The charge case 11, integralstems 12 and 80, and the pins 14 may all be made out of zinc alloy. Thisallows for the entire linked system 10 to be largely destroyed duringthe firing process. The zinc alloy is frangible and will shatter whenthe shaped charges fire. Zinc alloy also breaks apart into smallerpieces than a steel alloy design. Therefore, an advantage offered bythis configuration is that the linked system leaves very little largescale debris in the wellbore after firing and is completely expendable.The linked system 10 may also be used within a gun body. Theinterlocking stems 12 and 80 would replace the charge holder. Afterfiring, the gun body is removed from the wellbore with most of thedebris contained therein. Each shaped charge case 11 has a center linealong which the explosive output of a shaped charge will likely follow.

An example of one a shaped charge case 11 is shown in FIGS. 2A, 2B, and2C. In FIG. 2A a cross section of shaped charge case 11 shows that ingreater detail the difference between integral stem 12 and integral stem80. Integral stem 12 is a rectangular shaped key as further illustratedin FIG. 2C. Integral stem 80 has a variety of keyways 82 as furtherillustrated in FIG. 2B. The keyways 82 in this example are arranged toprovide 60 degrees of phase between each keyway. The shaped charge case11 when fully assembled into a shaped charge may also include a cap asshown in FIG. 11. The cap ensures the explosive material and the lineris sealed off from the borehole environment. The cap may be made out ofalloy steel or zinc alloy. The shaped charge case 11 also has a smallamount of material 16 that seals the explosive material off from theborehole. An explosive device, such as a detonating cord, is placed inretainer 17. When the detonating cord fires it will penetrate thematerial 16 and detonate the explosive material inside shaped chargecase 11.

An extension 21 as shown on FIG. 3 may be used to adjust the shotdensity and the phase angle. Adaptor 24 may interface with integral stem12. Adaptor 25 may interface with the keyways 82 of integral stem 80.The extension 21 has two holes, 22 and 23, for pins 14 to secure theextension 21 to the integral stems 24 and 25. The extension 21 allowsthe distance between each shot to increase. Also, the phase angle inthis example is adjustable using the extension 21.

Another example of the invention may include a rotated strip variant 30as shown in FIG. 4. In this example a series of strip segments 44 mayconnect to rotatable strip segments 45 as shown in FIG. 5. In thisexample the rotatable strip segment 45 has an adaptor 42 configured toaccept the keyway 45 of strip 44 at a variety of angles. The adaptor 42is fixed to the keyway 45 using guide caps 41. Guide caps 41 may snaptogether or screw to the adaptor 42. The strip segment 43 may also havean adaptor 47. The entire rotate strip variant 30 may be composed ofzinc allow in order to reduce the amount of large debris left in theborehole after firing. This design may also be used in a perforating gunwith a gun body. If used in a gun body, the rotated strip variant 30would replace the charge holder typically found in a perforating gun. Ifused inside of a perforating gun body the rotated strip variant 30 maybe composed of plastic instead of zinc alloy. Each strip segment 44 hasa through hole for fitting a shaped charge. In this example the throughhole 116 has an additional locking slot 115 that allows the shapedcharge to be installed at a specific orientation and then rotated untillocked into place at a second installed orientation.

Another example of the invention may include a modified loading stripconfiguration 50 as shown in FIG. 6A. In this example a conventionalloading strip 52 is used to hold the shaped charges 51. However, in thisvariant a phased bracket 53 may be used to orient the shaped charges 51as desired. This design allows for adjustable phase angles per shot andadjustable shot density. In this configuration all of the components maybe made of zinc alloy in order to reduce the likelihood of leaving largedebris in the wellbore after firing the shaped charges. However, thisdesign may also be used in a perforating gun with a gun body. If used ina gun body, the loading strip 52 would replace the charge holdertypically found in a perforating gun.

The side view of the loading strip 52 is presented in FIG. 6B. Theshaped charges 51 share a common axis that they are rotated about. Thetop view in FIG. 6C shows the shaped charges lined up and arrayed in 60degrees of phase between each shaped charge 51. Holes 54 allow theloading strip 52 to connect to downhole conveyance equipment includingwireline, coiled tubing, or mounted within a perforating gun casing.FIG. 6D shows the phased bracket 53. The phased bracket 53 is adapted tosnap or screw into the loading strip 52 as well as snap to the shapedcharges 51. The phased bracket 53 may also connect to the shaped chargesusing a threaded screw or other fastening means. In this example thephased bracket 53 has a ring portion adapted to accept a shaped charge.It has a base portion adapted to fit into a loading strip 52.Furthermore, it has two L-shaped support members that connect the baseportion to the ring portion. The L-shaped members are mirrors of eachother about the center axis of the circular base portion.

Another variation of the invention may include using a linked ringsystem 60 as shown in FIG. 7. In this configuration the shaped charges61 snap into place in a ring 70. The ring 70 has a male stem 72 andfemale stem 73 as shown in FIG. 8. The male stem 72 has holes 71arranged about the center axis every sixty degrees. The female stem 73has holes 75 arranged about the center axis every sixty degrees. Eachring 70 can be linked to another ring 70. A series of rings 70 can belinked together and the phase angle can be adjusted as desired.

Several of the examples shown use a sixty degree phase. A phase angle ofany range of angle values is appropriate, depending on the application.

Another variation of the invention is a twisted loading strip 90 asshown in FIG. 9. In this case the twisted loading strip 90 has a setcharge density and set phase angle. The shaped charges 92 are snapped orscrewed into place in the loading strip 91. The loading strip 91 in thisdesign may be composed of zinc alloy in order to reduce debris left inthe wellbore after firing. The shaped charge 92 also has a detonatingcord clip 93 and an end cap 94 to keep the outside environment fromentering the interior of the shaped charge 92. A variation of thetwisted loading strip 101 is shown in FIG. 10. This loading strip may becomposed of zinc alloy. This design is not as adaptable as the linkedsystem 10 shown in FIG. 1 because it has a preset shot density and phaseangle.

An example of a fully loaded shaped charge 18 is shown in FIG. 11.Integral stem 12 is a rectangular shaped key. Integral stem 80 has avariety of keyways 82 as further illustrated in FIG. 2B. The keyways 82in this example are arranged to provide 60 degrees of phase between eachkeyway. The shaped charge case 11 when fully assembled into a shapedcharge may also include a cap 112 attached over the shaped charge caselip 113. The cap 112 ensures the explosive material 110 and the liner111 is sealed off from the borehole environment. The cap 112 may be madeout of alloy steel or zinc alloy. The shaped charge case 11 also has asmall amount of material 16 that seals the explosive material off fromthe borehole. An explosive device, such as a detonating cord, is placedin retainer 17. When the detonating cord fires it will penetrate thematerial 16 and detonate the explosive material inside shaped chargecase 11. A centerline is formed from the apex of liner 111 through thesealed opening of shaped charge 18. This centerline corresponds to thepath an explosive jet will travel starting at the apex of liner 111 andheading out of the shaped charge 18, penetrating the cap 112 and likelyany wellbore or gun casing and into the surrounding formation.

Although the invention has been described in terms of particularembodiments which are set forth in detail, it should be understood thatthis is by illustration only and that the invention is not necessarilylimited thereto. Alternative embodiments and operating techniques willbecome apparent to those of ordinary skill in the art in view of thepresent disclosure. Accordingly, modifications of the invention arecontemplated which may be made without departing from the spirit of theclaimed invention.

What is claimed is:
 1. A perforating gun system comprising: a plurality of shaped charges linked directly to each other in a series; each shaped charge having a shaped charge case; each shaped charge case having a first stem and a second stem, wherein the first stem and the second stem are 180 degrees opposed to each other about the center axis of the shaped charge case.
 2. The perforating gun system of claim 1 wherein the first stem and second stem are integral to its associated shaped charge case.
 3. The perforating gun system of claim 1 wherein the first stem is a key.
 4. The perforating gun system of claim 1 wherein the second stem is a cylindrical socket with a plurality of internal slots adapted to accept a first stem from an adjacent shaped charge in a corresponding plurality of orientations.
 5. The perforating gun system of claim 4 wherein the socket of the second stem is configured to allow the first stem of an adjacent perforating shaped charge to interface with the second stem at a plurality of phase angles.
 6. The perforating gun system of claim 5 further comprising a plurality of pins, wherein the socket and the first stem have corresponding through holes that when lined up will accept one of the plurality of pins to effectively lock at least two shaped charges together.
 7. The perforating gun system of claim 1 further comprising a cap on each shaped charge adapted to seal the contents of the shaped charge case from an outside environment.
 8. The perforating gun system of claim 1 wherein the plurality of shaped charge cases and each accompanying first stem and second stem are composed of zinc alloy.
 9. The perforating gun system of claim 1 further comprising an extender located between two of the plurality of shaped charge cases, wherein the extender contains a plurality of slots on a first end and a key on the second end adapted to adjust the phase angle and shot density of the perforating gun system.
 10. The perforating gun system of claim 1 wherein each shaped charge is individually sealed using a cap placed over the charge case and using an O-ring to provide a water tight seal in a wellbore environment.
 11. The perforating gun system of claim 1 wherein the shaped charges are individually sealed.
 12. A shaped charge comprising: a shaped charge case having an opening; a liner; an explosive material between the liner and the shaped charge case; and the shaped charge case having a first stem and a second stem, wherein the first stem and the second stem are 180 degrees opposed to each other.
 13. The perforating gun system of claim 12 wherein the first stem and second stem are integral to the shaped charge case.
 14. The perforating gun system of claim 12 wherein the first stem is a male key.
 15. The perforating gun system of claim 12 wherein the second stem is a cylindrical female socket.
 16. The perforating gun system of claim 15 wherein the first stem and second stem is integral to a retainer ring that snaps into place over the shaped charge case.
 17. The perforating gun system of claim 12 further comprising a cap on the shaped charge adapted to seal the contents of the shaped charge from an outside environment.
 18. The perforating gun system of claim 17 further comprising an O-ring seal between each shaped charge and its associated cap.
 19. The perforating gun system of claim 12 further wherein the shaped charge case, first stem, and second stem are all composed of a zinc alloy.
 20. The perforating gun system of claim 12 further comprising a cap covering the opening of the shaped charge case, wherein the cap provides a water tight seal.
 21. The perforating gun system of claim 14 wherein the first stem is a rectangular male key.
 22. The perforating gun system of claim 15, the second stem further comprising a plurality of slots adapted to accept a first stem at a plurality of angles.
 23. A perforating gun system comprising: a plurality of shaped charge holder plates linked together in series, each holder plate having a male end connector and a corresponding female end connector.
 24. The perforating gun system of claim 23 wherein the corresponding female end connector is adapted to accept a male end connector at a plurality of phase angles.
 25. The perforating gun system of claim 23 further comprising a through hole on each holder plate sized to fit a shaped charge at a first orientation.
 26. The perforating gun system of claim 25, wherein the shaped charge is locked into place in the holder plate by rotating the shaped charge to a second orientation.
 27. The perforating gun system of claim 23 wherein the shaped charge holder plates are composed of zinc alloy.
 28. The perforating gun system of claim 23 wherein the linked shaped charge holder plates are placed inside a perforating gun body.
 29. A perforating charge holder comprising: a first ring configured to hold a perforating shaped charge at a preselected angle relative to a base configured to interface with a loading strip.
 30. The perforating charge holder of claim 29 wherein the first ring snaps to a shaped charge case.
 31. The perforating charge holder of claim 29 wherein the first ring screws into a shaped charge case.
 32. The perforating charge holder of claim 29 wherein the base screws into the loading strip.
 33. The perforating charge holder of claim 29 wherein the base snaps into the loading strip.
 34. The perforating charge holder of claim 29 further wherein the perforating charge holder is composed of zinc alloy.
 35. The perforating charge holder of claim 29 wherein the base is a second ring.
 36. The perforating charge holder of claim 29 further comprising a first L-shaped member with a first top and first bottom, and a second L-shaped member with a second top and a second bottom, wherein the first bottom and second bottom are attached to the base and the first top and second top are attached the ring such that the first L-shaped member and second L-shaped member mirror each other about a centerline of the base. 